All posts by Bryan Swopes

About Bryan Swopes

Bryan R. Swopes grew up in Southern California in the 1950s–60s, near the center of America's aerospace industry. He has had a life-long interest in aviation and space flight. Bryan is a retired commercial helicopter pilot and flight instructor.

24 April 1990, 12:33:51 UTC, T minus Zero

Discovery (STS-31) lifts off Pad 39B with the Hubble Space Telescope. Sister ship Columbia waits on Pad 39A. (NASA)
Discovery (STS-31) lifts off Pad 39B with the Hubble Space Telescope. Sister ship Columbia waits on Pad 39A. (NASA)

24 April 1990, 12:33:51 UTC: Space Shuttle Discovery (STS-31) lifted off from Launch Complex 39B at the Kennedy Space Center, Cape Canaveral Florida, on a mission to place the Hubble Space Telescope in Earth Orbit.

The STS-31 flight crew were Loren J. Shriver, Commander; Charles F. Bolden, Jr., Pilot; Steven A. Hawley, Mission Specialist; Kathryn D. Sullivan, Mission Specialist; Bruce McCandless II, Mission Specialist.

Discovery (STS-31) flight crew: Seated, left to right: Colonel Charles F. Bolden, Jr., U.S. Marine Corps; Colonel Loren J. Shriver, U.S. Air Force; Lieutenant Commander Kathryn D. Sullivan, U.S. Navy. Standing, left to right: Captain Bruce McCandless II, U.S. Navy; Mr. Steven A. Hawley. (NASA)
Discovery (STS-31) flight crew: Seated, left to right: Colonel Charles F. Bolden, Jr., U.S. Marine Corps¹; Colonel Loren J. Shriver, U.S. Air Force; Lieutenant Commander Kathryn D. Sullivan, U.S. Navy.² Standing, left to right: Captain Bruce McCandless II, U.S. Navy; Mr. Steven A. Hawley. (NASA)

The Hubble Space Telescope is named after Edwin Hubble, an early 20th century astronomer who discovered galaxies beyond our own Milky Way galaxy. It is an optical Ritchey–Chrétien telescope (an improved Cassegrain reflector). Star light enters the telescope and is collected by a large 7 foot, 10.5 inch (2.400 meter) diameter hyperbolic mirror at the back end. The light is reflected forward to a smaller hyperbolic mirror, which focuses the light and projects it back through an opening in the main reflector. The light is then gathered by the electronic sensors of the space telescope. These mirrors are among the most precise objects ever made, having been polished to an accuracy of 10 nanometers.

The Hubble Space Telescope being deployed from Disovery's cargo bay. (NASA)
The Hubble Space Telescope being deployed from Discovery’s cargo bay, 25 April 1990. (NASA)

The Hubble Space Telescope is 43.5 feet (13.259 meters long. The light tube has a diameter of 10 feet (3.048 meters) and the aft equipment section is 14 feet (4.267 meters) in diameter. The spacecraft weighs 27,000 pounds (12,247 kilograms).

The HST orbits the Earth every 97 minutes at an altitude of 320 nautical miles (593 kilometers). The telescope was last serviced in 2009. Originally designed to operate for 15 years, the HST is now in its 26th.

The Hubble Space Telescope in Earth orbit. (NASA)
The Hubble Space Telescope in Earth orbit. (NASA)

¹ Colonel Bolden reached the rank of Major General, United States Marine Corps, before retiring in 2003. He was served as Administrator, National Aeronautics and Space Adminstration, 17 July 2009–20 January 2017.

² Lieutenant Commander Sullivan left NASA in 1993, and retired from the U.S. Navy with the rank of Captain, in 2006. She served as Under Secretary of Commerce for Oceans and Atmosphere/Administrator, National Oceanic and Atmospheric Administration (NOAA), 28 February 2013–20 January 2017.

© 2017,  Bryan R. Swopes

23–24 April 1967

Colonel Vladimir Mikhailovich Komarov (Alexander Loktionov/RIA Novosti)

23–24 April 1967: At 00:35:00 UTC, 23 April, Soyuz-1, the first manned flight of the Soyuz 7K-OK spacecraft, was launched from Baikonur Cosmodrome Pad 1/5 (Gagarin’s Start). On this first test flight, only one person was aboard the craft, which had been designed to carry three cosmonauts. Colonel Vladimir Mikhailovich Komarov was the pilot. He had previously flown Voskhod-1, a 24-hour mission, in 1964.

A Soyuz 7K-OK space craft assembly. (Space Rocket History)
A Soyuz 7K-OK space craft assembly. (Space Rocket History)

The mission plan called for a second spacecraft, Soyuz-2, to be launched on the 24th, with a three-man crew. A rendezvous in orbit would be made.

Soyuz-1 was not ready to be flown. More than 200 faults were known, but the pressures brought about by politics required that the launch proceed.

On reaching orbit, two solar arrays were to deploy to provide electrical power for the spacecraft’s batteries. One panel did not deploy and this severely limited the power available.

The Soyuz stabilization system relied on sensors which would detect certain stars to provide orientation, but the failed solar panel covered them. Within a few orbits the system failed completely. Komarov used the ship’s thrusters to manually control stability, but this was only marginally effective.

There were also communications difficulties. With electrical power diminishing and reaction fuel being spent, the main goals of the mission could no longer be achieved. After 13 orbits it was decided to abort the mission.

An illustration of Soyuz-1
An illustration of Soyuz-1

Komarov had to manually align the Soyuz-1 during the daylight phase of orbit 18. Gyroscopic stabilizers were supposed to maintain that alignment as the spacecraft passed into darkness. Komarov would once again align the craft when it came around into light, and hold that alignment through the reentry deceleration.

For some reason, the braking engine was 2 minutes, 23.5 seconds late in firing. The deceleration burn was planned for 2 minutes, 30 seconds, but an automatic system, recognizing that the gyro system was not holding the proper alignment, cut off the engine 4 seconds early. This meant that the Soyuz would travel farther down range than intended, and would not have slowed quite as much, although it was enough for re-entry.

Soyuz-1 impacted the Earth at 03:22:52 UTC, 1.9 miles (3.06 kilometers) to the west of Karabutak, Orenburg Oblast, at speeds estimated at from 30–40 meters per second (67–89 miles per hour) to as high as 640 kilometers per hour (398 miles per hour). It is believed that Vladimir Komarov died from injuries sustained at this time.

He was the first person to die during a space flight.

A rescue helicopter quickly located the Soyuz reentry module which was lying on its side in an open field with its parachute alongside. The rescuers reportedly saw the soft-landing rockets fire, which they should have done just before the module’s impact.

The module was on fire and by the time rescuers reached it, it was fully involved and molten metal was spreading on the ground. After expending their fire extinguishers, the rescuers tried to put of the fire by shoveling dirt on to it, but the the capsule completely collapsed.

Doctors on the scene pronounced Vladamir Komarov dead, with injuries to his skull, spinal cord, and numerous broken bones resulting from the impact. His body was completely burned. A postmortem examination at Moscow confirmed that the cosmonaut had been killed by the capsule’s impact.

Colonel Vladimir Mikhailovich Komarov, Cosmonaut.
Lieutenant Colonel Vladimir Mikhailovich Komarov, Cosmonaut.

Several theories have been published as explanation for the failure of the spacecraft’s parachute to safely slow Komarov’s descent, though with the craft completely destroyed by fire, it is unlikely that there could be any certainty. The official finding is that the drogue parachute did not apply enough force to pull the main parachute free. A backup parachute was deployed manually by Komarov but it fouled in the drogue ‘chute and did not open sufficiently to brake the craft.

Another theory is that a pressure sensor malfunctioned which prevented the automatic deployment of the main parachute. The drogue ‘chute should have been released at that time, but was not, which resulted in the reserve parachute fouling.

Third is that during an autoclaving operation the parachutes may have been contaminated with an adhesive substance.

And another story is this: During the design of Soyuz-1, the thickness of the heat shield was increased, and so the weight of the spacecraft went up. Engineers increased the size of the main parachute accordingly. But the compartment that it was to be stored in remained the same size. The fit was so tight that when the parachute was being installed, technicians had to hammer it into place with wooden mallets.

 Burning wreckage of Soyuz-1, 24 April 1967. (RosCosmos)
Burning wreckage of Soyuz-1, 24 April 1967. (Russian Federal Space Agency)

Vladimir Mikhailovich Komarov was born at Moscow, Russian Socialist Federated Soviet Republic (RSFSR), 16 March 1927. His father was killed early in The Great Patriotic War (World War II). At the age of 15 years, Vladimir Mikhailovich entered the 1st Moscow Special Air Force School and graduated in 1945. He then went to Sasovskoye for initial pilot training, and then to the Borisoglebsk Air Force Pilot School. In 1946 he was transferred to the A.K. Serov Bataisk Military Aviation School. He received his pilot’s wings and was commissioned as a lieutenant in the Soviet Air Force, 10 December 1949.

Lieutenant Komarov served as a fighter pilot of the 383rd Fighter Aviation Regiment at Grozny. The regiment was transitioning from the Mikoyan-Guervich MiG-9 turbojet-powered fighter to the new swept-wing MiG-15. While there, he met his future wife, Valentina Yakovlevna Kiselyova, a recent graduate of the Grozny Teachers’ Training Institute. They were married in 1950. They had two children, Yevgeny and Irina.

In 1952, Senior Lieutenant Komarov was assigned as senior pilot of the 486th Fighter Aviation Regiment, flying the MiG-15 and MiG-17. In 1954 he applied to attend the N.E. Zhukovsky Air Force Engineering Academy, from which he graduated in 1959. Promoted to Senior Lieutenant-Engineer, he was assigned as a test pilot at the Central Scientific Research Institute.

Yuri Gagarin and Vladimir Komarov
Colonel Yuri Alexseyevich Gagarin and Lieutenant Colonel Vladimir Mikhailovich Komarov at Star City, 1964. (Europress/AFP)

After promotion to captain-engineer, 3 September 1960, Komarov was selected for the first group of Soviet cosmonauts. He was older than most of the group, but was well liked and respected.

Colonel-Engineer Vladimir Mihailovich Komarov, Pilot-Cosmonaut of the USSR, was twice named Hero of the Soviet Union. He had also been awarded the Order of Lenin, Order of the Red Star, as well as several other decorations.

Following a state funeral, the cosmonaut’s ashes were interred in the Kremlin Wall at Red Square.

Colonel Vladimir Mikhailovich Komarov, Pilot-Cosmonaut, Hero of the Soviet Union. “Whoever has flown once, whoever has piloted an airplane once, will never want to part with either an aircraft or the sky.”

© 2020, Bryan R. Swopes

24 April 1959

Boeing RB-47E Stratojet. (U.S. Air Force 050421-F-1234P-009)

24 April 1959: Captain John Stanley Lappo, United State Air Force, flies a Strategic Air Command Boeing RB-47E Stratojet UNDER the Mackinac Bridge. The suspension bridge spans the Straits of Mackinac, connecting the upper and lower peninsulas of the U.S. state of Michigan. The Straits of Mackinac connect the Great Lakes of Lake Michigan and Lake Huron.

The vertical clearance under the Mackinac Bridge at the center of the main span is 155 feet (47 meters). (Wikipedia)

The vertical gap between the highest point on the underside of the bridge’s main span is 155 feet (47.2 meters) above the surface of the water. The RB-47E has an overall height of 28 feet (8.5 meters). And Captain Lappo was flying at just 75 feet (23 meters).

Captain Lappo and his crew were returning to Lockbourne Air Force Base, southeast of Columbus, Ohio, following an overnight simulated bombing mission.

When asked why he did it, he answered: “Why do men climb mountains? Or what motivates them to go into space? It’s just a sense of adventure that some men have and some don’t. . . I’ve always wanted to fly under a big bridge. I thought it would be the Golden Gate. When I was flying missions to the Far East, I was a co-pilot, and I wanted to fly under the Golden Gate at night. But I couldn’t induce the pilot to do it.” ¹

The total length of the Mackinac Bridge is 26,372 feet (8,038 meters). The length of the main span is 3,800 feet (1,158 meters). The height of the main towers is 552 feet (168 meters). The bridge opened to traffic 1 November 1957. (Mackinac Bridge Authority)

Reported by his navigator, Captain Lappo was charged with violating a regulation prohibiting flying an aircraft below 500 feet (152 meters) (AF Reg 60–16). At his court-martial, he pleaded guilty. The court fined him $50.00 per month for six months and he received a reprimand. Based on this, Lieutenant General Walter Campbell Sweeney, Jr., Commanding General, Eighth Air Force, ordered him permanently removed from flight status.

John Lappo had been a highly respected pilot. Several senior officers testified at the court martial as to his skill, dedication and reliability.

John Stanley Lappo had enlisted in the U.S. Army Air Forces 19 February 1943 and was trained as a pilot. On completion of training he was given the warrant officer rank of flight officer. Lappo was commissioned as a second lieutenant in January 1945.

Lieutenant Lappo flew C-46, C-47 and C-54 transports with the 22nd Troop Carrier Squadron, 374th Troop Carrier Group, Fifth Air Force. He was released from active duty in 1948, but remained in the U.S. Air Force Reserve and maintained his flight status.

Flight Officer John Stanley Lappo, United States Army Air Forces, circa 1944. (Suzette Mizelle)

In 1951, Lieutenant Lappo was recalled to active duty for service in the Korean War. He flew 28 bombing missions in the Boeing B-29 Superfortess, including B-29-85-BN 44-87657, Command Decision, one of the best known bombers of the war.

John Stanley Lappo married Miss Olive Kay Robinson, 7 July 1951, at Muskegon, Michigan. He then attended Squadron Officers School at Maxwell AFB, Alabama.

As a B-47 Stratojet pilot, he was assigned to the 10th Strategic Reconnaissance Squadron, 26th Strategic Reconnaissance Wing, at Lockbourne AFB, and later, the 352nd Bombardment Squadron (Medium), 301st Bombardment Wing (Medium), which was also based at Lockbourne.

Captain Lappo was often given the most difficult assignments. As a reconnaissance pilot, he flew clandestine missions over the Union of Soviet Socialist Republics (USSR). For one of these missions he was awarded the Distinguished Flying Cross.

Lieutenant Colonel John S. Lappo, USAF

Even though he was permanently removed from flying duties, Lappo remained in the Air Force. He served in Southeast Asia during the Vietnam War, and was later vice commander of Elmendorf Air Force Base in Alaska. He rose to the rank of lieutenant colonel.

Lieutenant Colonel Lappo retired from the Air Force 31 July 1972.

John Stanley Lappo was born 8 January 1920 at Muskegon, Michigan. He was the fifth of seven children of Jan Stanislaw Lappo, a carpenter, and Zofia A. Stankiewicz Lappo.

In 1940 he was employed as a pattern maker at an iron foundry.

Lappo registered for the draft (conscription) 1 July 1941. The registrar’s report shows that he had brown hair, blue eyes, was 5 feet, 4½ inches (1.638 meters) tall and weighed 165 pounds (74.8 kilograms).

From 1972 to 1982, John Lappo worked for the state of Alaska as a regional administrator for the health department, then from 1982 to 1990, he operated a trucking company, Arctic Fox Trucking.

John Stanley Lappo died 15 November 2003 at Eagle River, Alaska. His remains are interred at the Fort Richardson National Cemetery, Anchorage, Alaska.

A Boeing RB-47E-1-BW Stratojet, 51-5259—the reconnaissance variant. (U.S. Air Force)

The Boeing RB-47E Stratojet was a reconnaissance variant of the B-47E strategic bomber. All RB-47Es were built by Boeing-Wichita. The type made its first flight 3 July 1953. 240 RB-47Es and 15 RB-47Ks were built, with the last one delivered in August 1955.

Designed by Boeing, the B-47 Stratojet was a high-subsonic speed strategic bomber and reconnaissance aircraft, in service from 1951 until 1977. The B-47 could fly higher and faster than jet fighters of the time, and it was also highly maneuverable. B-47 was flown by a two pilots in a tandem cockpit. A navigator was at a station in the nose. The RB-47E variant (Boeing Model 450-158-36) differed in that bombing equipment was deleted and photographic and electronic reconnaissance equipment installed. Additional fuel tanks were placed in the former bomb bay.

Illustration of RB-47E fuselage spaces. (U.S. Air Force)

The RB-47E Stratojet is slightly longer than the B-47E. The RB-47E is 109.8 feet (333.467 meters) long with a wingspan of 116.0 feet (35.357 meters), and an overall height of 28.0 feet (8.534 meters). The wings are shoulder-mounted and have a total area of 1,428 square feet (132.67 square meters). The wings’ leading edges are swept aft to 36° 37′. The angle of incidence is 2° 45′ and there is 0° dihedral (the wings were very flexible). The RB-47E had an empty weight of 81,100 pounds (36,786 kilograms) and maximum takeoff weight of 200,000 pounds (90,718 kilograms).

The RB-47E was powered by six General Electric J47-GE-25 turbojet engines in four nacelles mounted on pylons below the wings. This engine has a 12-stage axial-flow compressor, eight combustion chambers, and single-stage turbine. The -25 has a continuous power rating of 5,320 pounds of thrust (23.665 kilonewtons) at 7,630 r.p.m., at Sea Level; Military Power, 5,670 pounds (25.221 kilonewtons) at 7,800 r.p.m. (30 minute limit); and Maximum Power, 7,200 pounds (32.027 kilonewtons) at 7,950 r.p.m. with water/alcohol injection (5 minute limit). The J47-GE-25 has a maximum diameter of 3 feet, 1 inch (0.940 meters) and length of 12 feet, 0 inches (3.658 meters) and weighs 2,653 pounds (1,203 kilograms).

Boeing RB-47E-25-BW Stratojet 52-722, 26th Strategic Reconnaissance Wing, Lockbourne Air Force Base, Ohio, 1954. (Bob Garrard Collection/AirHistory.net/Flickr)

The RB-47E had a cruise speed of 433 knots (498 miles per hour/802 kilometers per hour), and maximum speed of 497 knots (572 miles per hour/920 kilometers per hour) at 20,000 feet (6,096 meters). The service ceiling was 47,800 feet feet (14,569 meters). Its unrefueled range was 3,935 nautical miles (4,528 statute miles/7,288 kilometers). The RB-47E was capable of inflight refueling and had a maximum fuel capacity of 18,280 gallons in six fuselage and two jettisonable wing tanks.

For defense the RB-47E was armed with two M24A1 20 mm autocannons with 350 rounds of ammunition per gun. The remotely-operated tail turret was controlled by the co-pilot through an A-5 fire control system.

A total of 2,032 B-47s were built by a consortium of aircraft manufacturers: Boeing Airplane Company, Wichita, Kansas; Douglas Aircraft Company, Tulsa, Oklahoma; Lockheed Aircraft Company, Marietta, Georgia.

The Stratojet is one of the most influential aircraft designs of all time and its legacy can be seen in almost every jet airliner built since the 1950s: the swept wing with engines suspended below and ahead on pylons. The B-47 served the United States Air Force from 1951 to 1977. From the first flight of the Boeing XB-47 Stratojet prototype, 17 December 1947, to the final flight of B-47E 52-166, was 38 years, 6 months, 1 day.

¹ “John Lappo Story,” by Wayland Mayo, at the web site  “B-29s Over Korea,” https://www.b-29s-over-korea.com/john-lappo-story/

© 2023, Bryan R. Swopes

24 April 1943

Graduating class of WASP Pilots pass in review.
Graduating class of WASP Pilots pass in review at Avenger Field, Sweetwater, Texas. (U.S. Air Force)

24 April 1943: The first class of the Women Airforce Service Pilots, Class 43-1, graduated from the four-month flight training program and earned their wings as U.S. Army pilots. The class entered with 38 trainees and 24 graduated. Each woman had a civil pilot’s license and at least 200 hours of flight time. Over 25,000 women applied and approximately 1,900 were accepted. By the end of the war, 1,074 had graduated.

Jacqueline (“Jackie”) Cochran, founder of the WASPs, seated in the cockpit of a Curtiss-Wright P-40 Warhawk. (U.S. Air Force)

The Women Airforce Service Pilots were civilian employees of the United States Department of War. Although the WASPs ¹ received the same primary, basic and advanced flight training as their U.S. Army Air Force male counterparts, they were not military personnel. Following graduation from their flight training, some pilots went on to specialized training in heavy bombers or fighters.

WASP pilots FrancesGreen, Margaret Kirchner, Ann Waldner and Blanche Osborne at the four-engine school at Lockbourne Army Airfield, Ohio, with a Boeing B-17. (U.S. Air Force)
WASP pilots Frances Green, Margaret Kirchner, Ann Waldner and Blanche Osborne at the four-engine school at Lockbourne Army Airfield, Ohio, with a Boeing B-17 Flying Fortress heavy bomber. (U.S. Air Force)
Test pilots were not always men. These four women, members of the Women Airforce Service Pilots (WASPs), were assigned as engineering test pilots, testing new aircraft and modifications. The airplane behind them is a North American Aviation B-25 Mitchell twin-engine medium bomber. From left to right, Dorothy Dodd Eppstein, Hellen Skjersaa Hansen, Doris Burmeister Nathan and Elizabeth V. Chadwick Dressler. (U.S. Air Force)
Test pilots were not always men. These four women, members of the Women Airforce Service Pilots (WASPs), were assigned as engineering test pilots, testing new aircraft and modifications. The airplane behind them is a North American Aviation B-25 Mitchell twin-engine medium bomber. From left to right, Dorothy Dodd Eppstein, Hellen Skjersaa Hansen, Doris Burmeister Nathan and Elizabeth V. Chadwick Dressler. (U.S. Air Force)

The WASPs were not combat pilots. They tested newly-manufactured aircraft for acceptance by the military, delivered these airplanes from factories to Air Corps bases around the country, ferried aircraft across oceans, and flew transport missions.

All of these women provided a great service to their country during a time of war, but even more so to the generations of women who would follow their path.

Major Eileen M. Collins with F-4E-31-MC Phantom II, 66-0289, at the Air Force Test Pilot School, Edwards Air Force Base, California, 1990. A pilot instructor on the T-38 Talon and C-141 Starlifter, Eileen Collins graduated from Class 89B at Edwards. Accepted as an astronaut for NASA, she piloted the space shuttle Discovery on mission STS-63, Atlantis, STS 84, and commanded Columbia STS-93 and Discovery, STS-114.(U.S. Air Force)
Major Eileen M. Collins with F-4E-31-MC Phantom II, 66-0289, at the Air Force Test Pilot School, Edwards Air Force Base, California, 1990. A pilot instructor on the T-38 Talon and C-141 Starlifter, Eileen Collins graduated from Class 89B at Edwards. Accepted as an astronaut for NASA, she piloted the space shuttle Discovery on mission STS-63, Atlantis, STS 84, and commanded Columbia STS-93 and Discovery, STS-114.(U.S. Air Force)
U.S. Air Force F-15C Eagle fighter Interceptor pilots of the 3rd Fighter Wing, Elmendorf AFB, Alaska, left to right, Major Andrea Misener, 19th FS; Captain Jammie Jamiesen, 12th FS; Major Carey Jones, 19th FS; Captain Samantha Weeks, 12th FS. (U.S. Air Force)
U.S. Air Force F-15C Eagle fighter Interceptor pilots of the 3rd Fighter Wing, Elmendorf AFB, Alaska, left to right, Major Andrea Misener, 19th FS; Captain Jammie Jamiesen, 12th FS; Major Carey Jones, 19th FS; Captain Samantha Weeks, 12th FS. (U.S. Air Force)
Captain Suzanna Darcy-Henneman, Lead Test Pilot for the Boeing 777 and Chief Pilot, Boeing Training and Flight Services. (Boeing)
Captain Suzanna Darcy-Henneman, Lead Test Pilot for the Boeing 777 and Chief Pilot, Boeing Training and Flight Services. (Boeing)
Brigadier General Jeannie Leavitt at Nellis AFB. (United States Air Force 160715-F-YM181-001)

¹ The WASPs were a separate organization from the WAFS, the Women’s Auxiliary Ferrying Squadron.

© 2019, Bryan R. Swopes

24 April 1939

The Curtiss XP-40 prototype at Langley Field in the original configuration. (NASA)
The Curtiss-Wright XP-40 prototype, 36-10, at Langley Field in the original configuration. Compare this to the first production P-40 Warhawk in the photograph below. (NASA)
Curtiss P-40 Warhawk 39-156. (U.S. Air Force)
Curtiss-Wright P-40 Warhawk 39-156. (U.S. Air Force)

24 April 1939: Curtiss-Wright’s prototype fighter, the XP-40 (Model 75P), was evaluated by the National Advisory Committee for Aeronautics (NACA) at the Langley Memorial Aeronautical Laboratory, Langley Field, Virginia, in March and April 1939. NACA engineers placed the XP-40 inside the Full-Scale Wind Tunnel, which was capable of accepting airplanes with wing spans of up to 40 feet (12.2 meters).

Compare this production Curtiss-Wright P-36A Hawk to the first production P-40 Warhawk in the photograph below.
Curtiss Model 81, P-40 Warhawk, 39-156. (San Diego Air and Space Museum Archive)

The airplane was a production Curtiss P-36A Hawk, serial number 38-10, which had been modified by replacing its original air-cooled Pratt & Whitney Twin Wasp S1C1-G (R-1830-17) 14-cylinder radial engine with a Harold Caminez-designed, liquid-cooled, supercharged, 1,710.597-cubic-inch-displacement (28.032 liter) Allison Engineering Co. V-1710-C13 (V-1710-19).

This was a single overhead cam (SOHC) 60° V-12 engine with four valves per cylinder and a compression ration of 6.65:1. It had a Normal Power rating of 910 horsepower at 2,600 r.p.m. at Sea Level, and 1,060 horsepower at 2,950 r.p.m. for Takeoff. At 10,000 feet (3,048 meters), the V-1710-19 had Maximum Continuous Power rating of 1,000 horsepower at 2,600 r.p.m., and Military Power rating of 1,150 horsepower at 2,950 r.p.m. The engine required 100/130-octane aviation gasoline. It drove a three-bladed Curtiss Electric constant-speed propeller through a 2:1 gear reduction.

The V-1710-19 was 8 feet, 1.75 inches (2.483 meters) long, 3 feet, 4.75″ (1.035 meters) high and 2 feet, 4.94 inches (0.735 meters) wide. It weighed 1,320 pounds (599 kilograms).

Curtiss XP-40 prototype in the NACA wind tunnel at Langley Field, Virginia, 24 April 1939. The technician at the lower left of the photograph provides scale. (NASA)
Curtiss-Wright XP-40 prototype in the NACA wind tunnel at Langley Field, Virginia, 24 April 1939. The technician at the lower left of the photograph provides scale. (NASA)

The primary benefit of the engine change was the streamlined fuselage that resulted. The new airplane was capable of a speed of 366 miles per hour (589 kilometers per hour), a 53 miles per hour (85 kilometers per hour) increase over the P-36.

Over a two-month period, NACA engineers made a number of improvements. The radiator was moved forward under the engine and the oil coolers utilized the same air scoop. The exhaust manifolds were improved as were the landing gear doors.

When they had finished, Lieutenant Benjamin Scovill Kelsey flew the modified XP-40 back to Curtiss at Buffalo, New York. Its speed had been increased to 354 miles per hour (570 kilometers per hour), a 12% improvement. Other improvements were recommended which may have increased the XP-40’s speed by an additional 18 miles per hour (29 kilometers per hour). By December 1939, the airplane had been further improved and was capable of 366 miles per hour (589 kilometers per hour).

These photographs show the full-size prototype in the NACA wind tunnel at Langley, 24 April 1939. Two days later, the U.S. Army Air Corps ordered 524 airplanes as the P-40 Warhawk. By the time production ended in 1945, 13,738 Warhawks had been built.

Curtiss XP-40 in the NACA full scale wind tunnel, Langley Field, Virginia, April 1939. (NASA)
Curtiss XP-40 in the NACA full scale wind tunnel, Langley Field, Virginia, April 1939. (NASA)

© 2018, Bryan R. Swopes